Problem solving in data structures and algorithms using java 1st edition

Week 1 Chapter 1: Introduction - Programming Overview Chapter 2: Algorithms Analysis Chapter 3: Approach To Solve Algorithm Design Problems Chapter 4: Abstract Data Type & JAVA Collectio

Problem Solving in Data Structures & Algorithms Using JAVA

First Edition

By Hemant Jain

in the case of very brief quotations embodied in critical reviews and certain other non-commercial uses permitted by copyright law

I would like to express profound gratitude to my guide/ my friend Naveen Kaushik for his

invaluable encouragement, supervision and useful suggestion throughout this book writing work.His support and continuous guidance enable me to complete my work successfully

Last but not least, I am thankful to Anil Berry and Others who helped me directly or indirectly incompleting this book

Hemant Jain

PROBLEMS IN STACK

PROS AND CONS OF ARRAY AND LINKED LIST IMPLEMENTATION OF STACK.USES OF STACK

OO DESIGN FOR A MCDONALDS SHOP

OBJECT ORIENTED DESIGN FOR A RESTAURANTOBJECT ORIENTED DESIGN FOR A LIBRARY SYSTEMSUGGEST A SHORTEST PATH

EXERCISE

APPENDIX

APPENDIX A

CHAPTER 0: HOW TO USE THIS BOOK

This book is about usage of data structures and algorithms in computer programming Datastructures are the ways in which data is arranged in computers memory Algorithms are set ofinstructions to solve some problem by manipulating these data structures

Designing an efficient algorithm to solve a computer science problem is a skill of Computerprogrammer This is the skill which tech companies like Google, Amazon, Microsoft, Facebookand many others are looking for in an interview Once we are comfortable with a programminglanguage, the next step is to learn how to write efficient algorithms

This book assumes that you are a JAVA language developer You are not an expert in JAVAlanguage, but you are well familiar with concepts of references, functions, arrays and recursion

At the start of this book, we will be revising the JAVA language fundamentals that will be usedthroughout this book We will be looking into some of the problems in arrays and recursion too

Then in the coming chapter we will be looking into Complexity Analysis Followed by thevarious data structures and their algorithms Will look into a Linked-List, Stack, Queue, Trees,Heap, Hash-Table and Graphs We will also be looking into Sorting, Searching techniques

And we will be looking into algorithm analysis of various algorithm techniques, we will belooking into Brute-Force algorithms, Greedy algorithms, Divide and Conquer algorithms,

Dynamic Programming, Reduction and Back-Tracking

In the end, we will be looking into System Design that will give a systematic approach to solvethe design problems in an Interview

Given the limited time you have before your next interview, it is important to have a solid

preparation plan The preparation plan depends upon the time and which companies you areplanning to target Below are the three-preparation plan for 1 Month, 3 Month and 5 Month

durations

1 Month Preparation Plans

Below is a list of topics and approximate time user need to take to finish these topics These arethe most important chapters that must to be prepared before appearing for an interview

This plan should be used when you have a small time before an interview These chapters cover90% of data structures and algorithm interview questions In this plan since we are reading aboutthe various ADT and JAVA collections in chapter 4 so we can use these datatype easily withoutknowing the internal details how they are implemented

Chapter 24 is for system design, you must read this chapter if you are three or more years ofexperienced Anyway, reading this chapter will give the reader a broader perspective of variousdesigns

Week 1

Chapter 1: Introduction - Programming Overview

Chapter 2: Algorithms Analysis Chapter 3: Approach To Solve Algorithm Design Problems

Chapter 4: Abstract Data Type & JAVA Collections

You will get a basic understanding of how to find complexity of a solution You will know how to handle new problems You will read about a variety of datatypes and their uses.

Week 2

Chapter 5: Searching Chapter 6: Sorting Chapter 14: String Algorithms

Searching, Sorting and String algorithm consists

of a major portion of the interviews.

Week 3

Chapter 7: Linked List Chapter 8: Stack Chapter 9: Queue

Linked list, Stack and Queue are one of the favorites in an interview.

Week 4

Chapter 10: Tree Chapter 23: Interview Strategy Chapter 24: System Design

This portion you will read about Trees and System Design You are good to go for interviews Best of luck.

3 Month Preparation Plan

This plan should be used when you have some time to prepare for an interview This preparationplan includes nearly everything in this book except various algorithm techniques Algorithmproblems that are based on dynamic programming divide & conquer etc Which are asked in vary

interview with them you can park these topics for some time and focus on the rest of the topics

Again, same thing here with system design problems, the more experience you are, the moreimportant this chapter becomes However, if you are a fresher from college, then also you shouldread this chapter

Week 1

Programming Overview Chapter 2: Algorithms Analysis Chapter 3: Approach To Solve Algorithm Design Problems Chapter 4: Abstract Data Type &

Chapter 1: Introduction -JAVA Collections

You will get a basic understanding of how to find complexity of a solution You will know how to handle new problems You will read about a variety of datatypes and their uses.

Week 2 &

Week 3

Chapter 5: Searching Chapter 6: Sorting Chapter 14: String Algorithms

Linked list, Stack and Queue are one of the favorites in an interview.

Week 6 &

Week 7

Chapter 10: Tree Chapter 11: Heap

This portion you will read about trees and heap data structures.

Week 8 &

Week 9

Chapter 12: Hash-Table Chapter 13: Graphs

Hash-Table is used throughout this book in various places, but now it’s time to understand how Hash-Table are actually implemented Graphs are used to propose a solution many real life problems.

Chapter 24: System Design

Interview strategy and system design chapter are the final chapters of this course.

Week 11 &

At this time, you need to revise all the chapters that we have seen in this book.

Whatever is left needs to be completed and the exercise that may be left needing to be solved in this period of time.

5 Month Preparation Plan

In this preparation plan is made on top of 3-month plan In this plan, the students should look foralgorithm design chapters In addition, in the rest of the time they need to practice more and morefrom www.topcoder.com and other resources If you are targeting google, Facebook, etc., Then it

is highly recommended to join topcoder and practice as much as possible

Chapter 1: Introduction - Programming

Week 2

Overview Chapter 2: Algorithms Analysis Chapter 3: Approach To Solve Algorithm Design Problems Chapter 4: Abstract Data Type & JAVA Collections

You will get a basic understanding of how to find complexity of a solution You will know how to handle new problems You will read about a variety of datatypes and their uses.

Week 3, Week

4 &

Week 5

Chapter 5: Searching Chapter 6: Sorting Chapter 14: String Algorithms

Searching, sorting and string algorithm consists of a major portion of the interviews Week 6, Week

7 &

Week 8

Chapter 7: Linked List Chapter 8: Stack Chapter 9: Queue

Linked list, Stack and Queue are one of the favorites in an interview.

Week 9 &

Week 10

Chapter 10: Tree Chapter 11: Heap

This portion you will read about trees and priority queue.

Week 11 &

Week 12

Chapter 12: Hash-Table Chapter 13: Graphs

Hash-Table is used throughout this book in various places, but now it’s time to

understand how Hash-Table are actually implemented.

Graphs are used to propose a solution many real life problems.

Chapter 16: Brute Force Chapter 17: Greedy Algorithm Chapter 18: Divide-And-Conquer, Decrease-And-Conquer

Chapter 19: Dynamic Programming Chapter 20: Backtracking And Branch- And-Bound

Chapter 21: Complexity Theory And Np Completeness

These chapters contain various algorithms types and their usage Once the user is familiar with most of this algorithm Then the next step is to start solving topcoder

Interview strategy and system design chapter are the final chapters of this course.

These are few preparation plans that can be followed to complete this book there by preparing forthe interview It is highly recommended that the user should read the problem statement first, then

he should try to solve the problems by himself and then only he should look into the solution tofind the approach of the book Practicing more and more problems will increase your thinkingcapacity and you will be able to handle new problems in an interview System design is a topicthat is not asked much from a fresher from college, but as you gain experience its importanceincrease We will recommend practicing all the problems given in this book, then solve more andmore problems from online resources like www.topcoder.com, www.careercup.com,

www.geekforgeek.com etc

PROGRAMMING OVERVIEW

This chapter emphasizes on brush up of the fundamentals of the JAVA Programming language Itwill talk about variables, references, classes, loops, recursion, arrays etc We assume that thereader is familiar with the syntax of the JAVA programming language and knows the basics ofObject-Orientation

It is tradition to discuss a HelloWorld program in the start which will print the phrase “Hello,World!” to the output screen So let us start discussing it This is a small program but it containsmany common features of all the JAVA programs

1. This program begins with “public class HelloWorld”:

a. A class is the basic unit of encapsulation Keyword class is used to create a new

class in our case class HelloWorld is created The class name is same as the name ofthe file, which will contain this class Therefore, in our case the name of the file isHelloWorld.java A class contains data and methods

b. The keyword public is an access specifier, which sets the accessibility of classes A

public class can be accessed from any class within the JAVA program

2. Next are the comments, which are for readability of the program and are ignored by thecompiler

4. System.out.println(“Hello, World!”) is a system provided method which will print “Hello,World! ” to the standard output

An Object is an entity with state and behavior A baby, a cat, a dog, a bulb etc are all examples

of objects A baby has properties & states (name, hungry, crying, sleeping etc.) and behaviors(feed, play, etc.) Another example a bulb have two states (on, off) and the two behaviors (turn

on, turn off)

Software objects are just like real world objects They have state in the form of member

variables called fields (isOn) and they expose behavior in the form of member functions called methods (turn on, turn off).

"Variables" are simply storage locations for data For every variable, some memory is allocated.The size of this memory depends on the type of the variable

Example 1.2:

public class variableExample {

public static void main(String[] args ) {

The various types of variable are defined as Data Types There are two varieties of data typesavailable in JAVA:

1. Primitive/ Basic Data Types

2. Reference Data Types

Example 1.3: Program demonstrating range of Primitive data type

public class MinMaxValueTest {

public static void main(String args []) {

byte maxByte = Byte.MAX_VALUE;

byte minByte = Byte.MIN_VALUE;

short maxShort = Short.MAX_VALUE;

short minShort = Short.MIN_VALUE;

int maxInteger = Integer.MAX_VALUE;

int minInteger = Integer.MIN_VALUE;

long maxLong = Long.MAX_VALUE;

long minLong = Long.MIN_VALUE;

float maxFloat = Float.MAX_VALUE;

float minFloat = Float.MIN_VALUE;

double maxDouble = Double.MAX_VALUE;

double minDouble = Double.MIN_VALUE;

System.out.println( "Range of byte :: " + minByte + " to " + maxByte);

System.out.println( "Range of short :: " + minShort + " to " + maxShort);

System.out.println(" Range of integer :: "+ minInteger + " to " +maxIntege); System.out.println( "Range of long :: " + minLong + " to " + maxLong); System.out.println( "Range of float :: " + minFloat + " to " + maxFloat); System.out.println( "Range of double :: " + minDouble + " to " + maxDouble); }

Arguments can be passed from one method to other using parameters All the basic data typeswhen passed as parameters are by the passed-by-value That means a separate copy is createdinside the called method and the variable in the calling method remains unchanged

Reference variables are used to store memory address of classes as well as arrays Any variableother them 8 primitive data types are reference data type

Parameter passing of a reference variable is done by copying the address of the variable Thismethod is called pass-by-reference Since the object is not copied, it is shared, the changes done

If you need to change the value of the parameter inside the method, then you should use call byreference JAVA language by default passes by value Therefore, to make it happen, you need topass the address of a variable and changing the value of the variable using this address inside thecalled method

Points to remember:

1. Call by reference is implemented indirectly by passing the address of an instance of class

or array to the function

There are three types of methods Class Methods, Instance Methods and Constructors By default,all the methods are instance methods

5. The special keyword “this” is valid only inside instance methods (and invalid inside classmethods ) as “this“ refers to the current instance

Constructor: It is a special kind of method, which is invoked over objects when they are created.

Constructor methods have the same name as the class Constructor method is used to initialize thevarious fields of the object For the class that does not have constructors, JAVA language providesdefault constructors for them

Access modifiers are used to set the visibility level to the class, variables and methods JAVAprovide four types access modifiers: default, public, protected, private

Objects define their interface as the interaction with the outside world For example, in the bulbcase switch is the interface between you and the bulb You press the button turn on and the bulbstart glowing

Example 1.7:

public inte rface BulbInterface {

public void turnOn();

public void turnOff();

These are the various relationships that exist between two classes:

Dependency: Objects of one class use objects of another class temporarily When a class creates

an instance of another class inside its member method and use it and when the method exits, thenthe instance of the other class is deleted

An abstract method is a method which does not have a definition Such methods are declared withabstract keyword

A class which has at least one abstract method need to be declared as abstract We cannot createobjects of an abstract class (A class which does not have any abstract method can also be

public class Circle e xte nds Shape {

private double radius ;

public class ShapeDemo {

public static void main(String[] args ) {

double width = 2, length = 3;

Shape rectangle = ne w Rectangle( width , length );

System.out.println( "Rectangle width: " + width + " and length: " + length

+ " Area: " + rectangle area()

+ " Perimeter: " + rectangle perimeter());

double radius = 10;

Shape circle = ne w Circle( radius );

System.out.println( "Circle radius: " + radius

+ " Area: " + circle area()

+ " Perimeter: " + circle perimeter());

Example 1.12:

public class LinkedList {

private static class Node {

private int value ;

private Node next ;

private int value ;

private Node lChild ;

private Node rChild ;

// Nested Class Node other fields and methods }